Alkoxy-benzyl-dithiocarbamic acid esters as selective herbicides

ABSTRACT

ALKOXY-BENZYL-DITHIOCARBAMIC ACID ESTERS, I.E. ALKOXYBENZYL- -N-ALKYL-, -N,N-DIALKYL- AND PIPERIDINO-DITHIOCARBAMIC ACID ESTERS, WHICH POSSESS HERBICIDAL PROPERTIES, AND WHICH MAY BE PRODUCED BY CONVENTIONAL METHODS.

United States Patent Oflice 3,726,661 ALKOXY-BENZYL-DITHIOCARBAMIC ACID ESTERS AS SELECTIVE HERBICIDES Kiyoshi Matsushima, Masao Miyamoto, and Nobuo Fukazawa, all of Nikon Tokushu Noyaku Seizo K.K., Tokyo, Japan No Drawing. Application Dec. 8, 1969, Ser. No. 883,344, which is a continuation-in-part of application Ser. No. 840,068, Mar. 6, 1969. Divided and this'application Dec. 7, 1971, Ser. No. 205,761

Int. Cl. A01n 9/12 U.S. Cl. 71-101 4 Claims ABSTRACT OF THE DISCLOSURE Alkoxy-benzyl-dithiocarbamic acid esters, i.e. alkoxybenzyl- -N-alky1-, -N,N-dialkyland piperidino-dithiocarbamic acid esters, which possess herbicidal properties, and which may be produced by conventional methods.

This is a division of copending U.S. application Ser. No. 883,344, filed Dec. 8, 1969, now U.S. Pat; No. 3,658,- 871, which is a continuation-in-part application of copending U.S. application Ser. No. 840,068, filed Mar. 6, 1969 now abandoned.

The present invention relates to and has for its objects the provision for particular new alkoxy-benzyldithiocarbamic acid esters, i.e. alkoxy-benzyl- -N-alkyl-, -N,N-dialkyl and piperidino- -dithiocarbamic acid esters, which possess herbicidal properties, active compositions in the form of mixtures of such compounds with solid and liquid dispersible carrier vehicles, and methods for producing such compounds and for using such compounds in a new way especially for combating weeds, undesired plants, and the like, with other and further objects becoming apparent from a study of the within specification and accompanying examples.

Pentachlorophenol (A), often designated as PCP, is known to be usable for controlling barnyard grasses, (e.g. Echinochloa sp.). However, PCP is remarkably toxic to human skin and mucous membranes, is very difficult to formulate into herbicidal compositions, and exhibits a peculiar toxicity to fish life. For the control of simultaneously occurring slender spikerushes (Eleocharis acicularis), 2-methyl-4-chloro-phenoxyacetic acid (B), often designated as MCP, is similarly usable. A disadvantage of using MCP as a herbicide, however, is that while it is effective against slender spikerushes it is not effective for the control of barnyard grasses. Hence, a mixture of PCP and MCP is employed conventionally for simultaneous control of barnyard grasses and slender spikerushes, especially in rice cultivations, since these two weeds normally occur in rice paddies. 1

It has now been found, in accordance with the present invention, that the particular new alkoxy-benzyl-dithiocarbamic acid esters of the formula an le Z is lower alkylamino, dilower alkylamino or piperidino,

exhibit strong herbicidal, especially selective herbicidal, properties.

It has been furthermore found, in accordance with the present invention, that a process for the production 3,726,661 Patented Apr. 10, 1973 of the particular new compounds of Formula I above may be provided, which comprises reacting an alkoxybenzyl halide of the formula -cmnal (II) in which R is the same as defined above, and

Halls a halogen atom such as chloro, bromo, fiuoro or iodo, especially chloro, with a dithiocarbamic acid compound of the formula s M-S-ii-Z (III) in which Z is the same as defined above, and

M is a hydrogen atom, an alkali metal atom such as sodium, potassium, lithium, and the like, or an ammonium group.

Surprisingly, the particular new alkoxy-benzyl-dithiocarbamic acid esters according to the present invention exhibit both a higher and more specific herbicidal effectiveness than the previously known pentachlorophenol (A) and 2-rnethyl-4-chloro-phenoxyacetic acid (B), especially against weeds inrice cultivations, and particularly a herbicidal effect against both barnyard grasses and slender spikerushes which occur together in rice paddy cultivations, while also exhibiting a comparatively low toxicity to warm-blooded animals and fish life and a concomitantly low phytotoxicity to higher plants such as rice. The active compounds of the present invention exhibit a characteristic selectivity among plants of the Graminae family, especially as between barnyard grasses and rice, which is ascribable to the differences in root absorption therebetween and which results in said very low phytotoxicity to rice plants. Moreover, the instant compounds are capable of controlling weeds without any disturbing influence by reason of their application at the time of tillering, prior to transplanting, a practice which has not been found appropriate heretofore. Therefore, the instant compounds represent a valuable contribution to the art.

The general process for the preparation of the instant compounds is illustrated by the following reaction scheme:

The starting materials to be used are already known and are clearly characterized by the Formulae l1 and III stated above. 7

Advantageously, in accordance with the present invention, in thev'arious formulae herein:

R represents straight and branched chain lower alkyl hydrocarbon such as methyl, ethyl, nand iso-propyl, n-, iso-, sec.- and tert.-butyl, nand iso-amyl, nand isohexyl', and the like, especially C or (2 or C alkyl, and more especially 2-, 3- or 4-positiou lower alkyl, such that R is 2-, 3- or 4-position lower alkoxy; and

Z represents alkylamino such as methyl to isohexyl inelusive, as defined above, and the like, -amino, especially C 4 or C or C or C, alkylamino, and more especially methylamino; or dilower alkylamino such as di- (same or mixed) methyl to isohexyl inclusive, as defined above, and the like, -amino, especially di C or C or C or C alkylamino, and more especially dimethylamino; or piperidino.

Preferably, R is C or Cf' alkyl; and Z is mono or di C alkylamino or piperidino.

As examples of alkoxy-henzyl halides of Formulae II above which may be used as starting materials, there are mentioned: 2-, 3- and 4-methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec.-butoxy, tert.- butoxy, n-amyloxy, isoamyloxy, n-hexyloxy, isohexyloxy, and the like, benzyl-chlorides, bromides, fluorides and iodides.

As examples of dithiocarbam-ic acid compounds of Formula III above which may be used as starting materials, there are mentioned: N- and N,N-di-methyl, ethyl, n-pr opyl, isopropyl, n-butyl, isobutyl, sec.-butyl, tert.- 'butyl, n-amyl, isoamyl, n-hexyl, isohexyl, and the like, as well as piperidino, -dithiocarbamic acids, and the corresponding sodium, potassium, lithium and ammonium salts, and the like.

Suitable inert organic solvents include hydrocarbons, such as benzine and benzene; chlorinated hydrocarbons, such as methylene chloride, ethylene chloride, carbon tetrachloride and dichlorobenzene; ethers, such as diethyl ether, dibutyl ether and dioxan; ketones, such as acetone, cyclohexanone and methylethyl ketone; alcohols such as methanol, ethanol, propanol and butanol; and acetonitrile and dimethyl formamide; and the like.

A basic substance, preferably a tertiary amine or an alkali metal hydroxide or carbonate, such astrlethylamine, pyridine, dimethyl-cyclohexylamine, dimethylaniline, dimethyl-benzylamine, sodium hydroxide, potassium hydroxide, sodium carbonate, and the like, may be added as acid-binding agent Where the free dithiocarbamic acid, rather than alkali metal or ammonium salt, is used.

The reaction temperature can be varied within a fairly wide range. In general, the reaction is carried out at substantially between about 40-120 (2., preferably at between about 60-110 C.

Approximately equimolar amounts of the starting materials are preferably used, although an excess of one of the reactants is not detrimental. Usually the alkoxybenzyl halide is added to a heated solution of the starting dithiocarbamic acid compound in an inert organic solvent and the mixture is refluxed for about 1-3 hours, and then filtered from the salt precipitate. The filtrate is concentrated and the final compound often crystallizes upon standing. Such crystals can be purified by recrystallization from a suitable solvent, such as-alcohol. Where the free dithiocarbamic acid is used, an alkali metal hydroxide or carbonate or a tertiary amine may be added to the reaction mixture as acid-binding agent.

..The resulting finalcompounds are either oily or crystalline substances which are soluble in the usual organic solvents while being only difiicultly soluble in water.

Advantageously, the particular new active compounds according to the present invention exhibit strong herbicidal activity and are distinguished by a selective herbicidal activity against weeds, especially in rice cultivations. Their low toxicity to warm-blooded animals and their good compatibility with higher plants. permits the instant new compounds to be used as excellent plant protection agents against weeds. In the concentrations normally used for the control of weeds, the instant compounds do not damage cultivated plants.

By weeds are meant in the wides sense all plants which grow in cultivations, especially rice paddy cultivations, or in other places where they are not desired.

The particular new active compounds according to the present invention are particularly effective against rice paddy weeds, such as barnyard grasses (Echinochola) and slender spikerushes (EleOcharis acicularis) as well as broadleaf weeds including, for instance, Rotala indica Koehne var., ulz'ginosa Miquel, Monochoria vaginalis PresL, false pimpernels (Lindernia pyxidari Linnaeus), and the like.

By reason of their excellent properties mentioned above, the particular new active compounds according to the present invention can thus be used with especially effective results against rice paddy weeds which hitherto had to be controlled with herbicidal agents which were somewhat harmful to man and fish life, and moreover for the joint and simultaneous control of both barnyard grasses and slender spikerushes. This is a substantial advantage, i.e. in agriculture, both from a labor-saving and an economical standpoint, since up to now, as aforesaid, agents from different chemical groups or classes usually had to be used, respectively, against these two types of weeds.

The active compounds according to the instant invention can be utilized, if desired, in the form of the usual formulations or compositions with conventional inert pesticidal diluents or extenders, i.e. conventional pesticidal dispersible carrier vehicles, such as solutions, emulsions, suspensions, emulsifiable concentrates, wettable powders or spray powders, pastes, aerosols, oils, soluble powders, dusting agents, granules, pellets, tablets, etc. These are prepared in known manner, for instance by extending the active compounds with conventional pesticidal dispersible liquid diluent carriers and/or dispersible solid carriers optionally with the use of carrier vehicle assistants, e.g. conventonal pestidical surface-active agents, including emulsifying agents and/or dispersing agents, whereby, for example, in the case where water is used as diluent, organic solvents may be added as auxiliary solvents. The following may be chiefly considered for use as conventional carrier vehicles for this purpose: inert dispersible liquid diluents or carriers including inert organic. solvents and non-solvents (e.g. non-solvents which can disperse or dissolve the active compounds with the aid of adjuvants), such as aromatic hydrocarbons (e.g. benzene, toluene, xylene, dimethyl naphthalene, aromatic naphthas, etc.), halogenated, especially chlo rinated, aromatic hydrocarbons (e.g. chlorobenzenes,

' etc.), paratfins (e.g. petroleum fractions), chlorinated aliphatic hydrocarbons (e.g. methylene chloride, etc.), alcohols (e.g. methanol, ethanol, propanol, butanol, etc.), amine (e.g. ethanolamine, etc.), ethers, etheralcohols (e.g. glycol monomethyl ether, etc.), amides (e.g. dimethyl formamide, etc.), sulfoxides (e.g. dimethyl sufoxide, etc.) ketones (e.g. acetone, etc.), and/or water; as well as inert dispersible finely divided solid carriers, such as ground natural minerals (e.g. kaolins, alumina,

. silica, chalk, i.e. calcium carbonate, talc, kieselguhr,

etc.); and/or dispersing agents, such as lignin, sulfite waste liquors, methyl cellulose, etc.

Such active compounds may be employed alone or in the form of mixtures with one another and/or with such solid and/or liquid dispersible carrier vehicles and/or with other known compatible active agents, especially plant protection agents, such as other herbicides, or fungicides, insecticides, acaricides, nematocides, bactericides, plant growth controlling agents, etc., including organo-phosphorus compounds, carbamate compounds, chlorinated compounds, dinitro compounds, organic sulfur or copper compounds, substituted phenoxy compounds, chlorophenols, substituted diphenyl ethers, anilide compounds, triazine compounds, urea compounds, antibiotics, and other known agricultural chemicals and/ or fertilizers and their adjuvants including wetting agents and adhesive agents, if desired, or in the form of particular dosage preparations for specific application made therefrom, such as solutions, emulsions, suspensions, powders, pastes, and granules which are thus ready for use.

As concerns commercially marketed preparations, these generally contemplate carrier composition mixtures in which the active compound is present in an amount substantially between about 01-95%, and preferably 05-90%, by weight of the mixture, whereas carrier composition mixtures suitable for direct application or field application generally contemplate those in which the active compound is present in an amount substantially between about 0.00l30%, preferably 0.055%, by weight of the mixture. Thus, the present invention contemplates over-all compositions which comprise mixtures of a conventional dispersible carrier vehicle such as (1) a dispersible inert (finely divided carrier solid, and/or (2) a dispersible liquid such as an inert organic solvent or non-solvent and/or water, preferably including a surface-active effective amount of a carrier vehicle assistant, e.g. a surface-active agent, such as an emulsifying agent and/or a dispersing agent, and an amount of the active compound which is effective for the purpose in question and which is generally about 0.00195%, and preferably 0.05-95%, by weight of the mixture.

In particular, the amount of active compound per unit area varies according to the purpose intended and the mode of application. In general, substantially between about -1000 grams, preferably 100-600 grams, of active compound per 10 acres are applied.

The active compound can also be used in accordance with the well-known ultra low-volume process with good success, i.e. by applying such compound if normally a liquid, or by applying a liquid composition containing the same, via very effective atomizing equipment in finely divided form, e.g. average particle diameter of from 50- 100 microns; or even less, i.e. mist form, for example by airplane crop spraying techniques. Only up to at most about a few liters/hectare are needed, and often amounts only up to about 1 quart/acre, preferably 2-16 fluid ounces/acre, are suflicient. In this process it is possible to use highly concentrated liquid compositions with said liquid carrier vehicles containing from about 20 to about 95% by weight, of the active compound, or even the 100% active substance alone, e.g. about 20-100% b weight of the active compound.

In particular, the present invention contemplates methods of selectively killing, combating or controlling undesired plants, e.g. weeds and the like, which comprise applying to at least one of (a) such weeds and (b) their habitat, i.e. the locus to be protected, a herbicidally effective or toxic amount of the particular active compound of the invention alone or together wih a carrier vehicle as noted above. The instant formulations or compositions When used in higher quantities per unit area (e.g. between about 20-40 kg. of active com-pound per hectare) the instant compounds are non-selective herbicides, whereas when used at lower quantities per unit area (e.g. between about 2.5-5 kg. of active compound per hectare) such compounds are excellent selective herbicides.

The active compounds are especially effective as preemergence herbicides, although they may also be used as post-emergence herbicides.

It will be realized, of course, that the concentration of the particular active compound utilized in admixture with the carrier vehicle will depend upon the intended application. Therefore, in special cases, it is possible to go above or below the aforementioned concentration ranges and ranges of amounts per unit area.

The following illustrate, without limitation, examples of formulations which may be used in accordance with the present invention:

FORMULATION A Five percent by weight of 4-methoxy-benzyl-N,N- dimethyl-dithiocarbamate (4) and by weight of a mixture of talc and clay (3:1) are crushed and mixed to form a dust formulation. It is applied as is by dusting onto weeds and/ or their habitat.

FORMULATION B Twenty percent by weight of 2-methoxy-benzyl-N,N- dimethyl-dithiocarbamate (8), 75% by weight of a mixture of talc and clay (3:2), 3% by weight of sodium alkylbenzene-sulfonate, and 2% by weight of sodium dinaphthylmethane disulfonate are mixed and pulverized to form a wettable powder which is diluted with water to a concentration of 1 to 500 and applied by spraying onto weeds and/ or their habitat.

FORMULATION C Twenty percent by weight of 4-methoxy-benzyl-N,N- di-n-propyl-dithiocarbamate (7), 75% by weight of xylol, and 5% by weight of the emulsifier Sorpol (trade name of the product of Toho Kagaku Kogyo k.k., Japan: polyoxyethylcnealkylarylether are mixed and stirred to form an emulsion which is diluted with water to a concentration of l to 1000 and applied by spraying onto weeds and/or their habitat.

FORMULATION D 4-methoxy-benzyl-N,N-diisopropyl-dithiocarbamate (6) is dissolved in xylol while heating. The resulting solution is sprayed onto granular clay during rotary mixing of the mass until about 10% by weight of the active compound is contained in the clay. The resulting granular composition is used by applying directly to the surface of soil.

The herbicidal effectiveness of the particular new compounds of the present invention is illustrated, without limitation, by the following examples:

Example 1.Test against weeds of paddy fields Preparation of active compounds:

Carrier vehicle5 parts by weight of acetone or 5 parts by weight of talc Emulsifier-1 part by weight of benzyloxypolyglycolether To produce a suitable preparation of the particular active compound, 1 part by weight of such active compound is mixed with the stated amount of carrier vehicle and the stated amount of emulsifier intimately, and the resulting emulsifiable concentrate or wettable powder is then diluted with water to the desired final concentration.

Test method: Pots of %,000 a. are charged with paddy field soil and then filled with water. Paddy rice seedlings (Jukkoku variety) of 3 leaves stage are transplanted into the pots under irrigated conditions. After the seedlings have taken root, seeds of barnyard grass and broad-leaved weeds are sown and spikerush are planted in such pots simultaneously.

The preparations of the given active compound are sprayed at the rate of 500, 250 and 125 g. of active compound per 10 a. onto the soil of pots. After 3 weeks, the degree of damage against the barnyard grass spikerush and broad-leaved weeds and the phytotoxicity to the paddy rice are deter-mined and characterized by the values to 5, which have the following scales:

HERBICIDAL EFFICACY The particular active compounds tested, the amounts used, and the results obtained can be seen from the following Table 1:

TABLE L-TEST RESULTS OF HERBICIDAL EFFECT Pro-emergence Herbicidal efiect Broad- Phytoleaved toxiciweeds ty,r1ce

Concentration of active compound in g. acres Barn Slender yard spikegrass rush Active compound number C ompoun ds of invention scum were wa fi wo en new: 9201C was. o-cnocomm wool more! 010:0 mew-o1 up up we: own maven comm NW :acacn wow who. rho-m cacao woven we nowown O00 O06 00 GOO O00 O00 OQO O60 GOO GOO GOO COO Q00 TABLE tt-Gontinued Concentra- Herbicidal etiect tion of active com- Barn- Slender Broad- Phyto- Actlve compound pound in yard spikeleaved toxicinumber gJlO acres grass rush weeds ty, rice Known compoundscomparison:

(A) POP (Commerclal grade control) 1, 000 5 5 5 1 500 3 2 4 0 250 0 0 2 0 (B) MOP (Commercial gradecontrol) 50 5 5 (G) Benzyl- N ,N-dimethyl dithlocarbamate (control) 500 5 5 5 0 250 4 2 4 0 125 2 1 2 0 (D) S-benzyl- N,N "sopropyl-thiolcab bamate 500 5 5 5 4 250 4 4 4 3 125 3 2-3 3 1 Non-treated 0 0 O 0 Norns:

Compounds of invention have corresponding numbers to those in Table 2 below.

Broad-heaved weeds are Monochorz'a vaginalis. Rotala indica. Lindernia pyzzdnria, Gratiola japo'nicu, etc.

The following further examples illustrate, without limitation, the process for producing the particular new compounds of the present invention.

Example 2.-4-methoxy-benzyl-N,N-dimethyldithiocarbamate (4 Sodium N,N-dimethyl-dithiocarbamate (28.6 g.-0.2 mol) are introduced into a 500 ml. three-necked flask, and dissolved by addition of 300 ml. of acetone thereto. The resulting solution is heated and then refluxed over a water bath, and while stirring, a solution of 31.3 g. (0.2 mol) of 4-rnthoxy-benzyl chloride in 50 ml. of acetone is added dropwise. After the addition has been completed (requiring about 30 minutes), the mixture is refluxed for an additional 2 hours. At the end of the reaction, the resulting reaction mixture is cooled. The salt precipitate is separated by filtration. The filtrate is concentrated, and left to stand in a cold place so that the intended final product crystallizes. The obtained crude crystals are recrystallized from alcohol to give 42.4 g. of 4-methoxybenzyl-N,N-dimethyl-dithiocarbamate in the form of colorless crystals having a melting point of 65-67 C. (yield 88% of theory) Elemental analysis-Calculated (percent): C, 54.74; H, 6.31; N, 5.82. Found (percent): C, 54.12; H, 5.91; N, 5.97.

Example 3.--4-methoxy-benzyl-N,N-diisopropyldi-thiocarbamate (6 Twenty grams (0.1 mol) of sodium N,N-diisopropyldithiocarbamate are mixed with ml. of methyl-ethyl 9 ketone, and the mixture is introduced into a 300 ml. threenecked flask. The mixture is heated to 8085 C. over a water bath, and while stirring, a solution of 16 g. (0.1 mol) of 4-methoxybenzy1 chloride in 50 m1. of methylethyl ketone are added dropwise. After the addition has 10 are recrystallized from alcohol to give 27.3 g. of 4- methoxy benzyl N,N diisopropyldithiocarbamate in the form of colorless crystals having a melting point of 116-118 C. (yield 91.6% of theory) Elemental analysis.Calculated (percent): C, 60 .60;

5 been completed (requiring about 15 minutes), the result- H, 7.79; N, 4.71. Found (percent): C, 59.87; H, 7.81; ing mixture is heated at 85-95" C. for an additional hour N, 4.53, to complete the reaction. The resulting reaction mixture In analogous manner, other compounds of the present is cooled, and the salt precipitate is separated by filtration. invention can be readily synthesized as well. The filtrate is concentrated under reduced pressure, and 10 The following Table 2 illustrates appropriate data for left to stand while cooling. Crude crystals of the intended typical compounds of the present invention. final product are thereby obtained. The crude crystals TABLE 2 Compound Structural formula Chemical name Properties 1; i /H 4-methoxy-banzyl-N-methyldithiocarbamate-. M.P.=88-89 0.

cH.0-o11,s-o1v 2; i /H 4-methoxy-benzyl-N-ethyldithiocarbamate-... M.P.=58-59 0.

CHaOCHaSCN\ CgH 3: S OH; -methoxy-benzyl-N-methyl-N-n-butyl- B.P.=l89-19l 0./0.4 mm. Hg.

ll dithlocarbamate. CHaO H2S-C-N\ C4Ho-n 4; S OH; 4-methoxy-benzyl-N,N-dimethyldlthto- M.P.=6567 0. II carbamate. CHsO CH2S-CN\ S 01H; 4-methoxy-benzyl-N,N-diethyldithio- M.P.=3334 0.

carbamate. CHaO- CH2S-CN\ 61 S C3H1'i 4-methoxy-benzyl-N,N-diisopropyldlthio- M.P.=116-118 C.

| carbamate. OHzO CHzSC-N\ CaH1-i 71 S 0sH1-n 4-methoxy-benzyI-N,N-di-n-propyldlthio- B.P.=178179 C./0.3 mm. Hg.

ll carbamate. CHaO 0H2S0N\ 0aH1-n 8: 0 CH; Z-methoxy-benzyl-N,N-dimethyldlthlocarba- B.P.=167169 0./0.03 mm.

I |SI /0H mate. Hg. (M.P.=6970 0.). @cm-s-o-rr 9: 0 CH: 2-methoxy-benzyl-N,N-diethyldithlocarba- B.P.=167169 0./O.1 mm. Hg.

|S /C2Hs mate. --CHzSC--N CgH 10-1 O CH; 2-methoxy-benzyl-N,N-dlisopropyl dlthio- M.P.=8789 0.

l i C s -l-i carbamate.

11: CHzO 3-methoxy-benZyl-N,N-dimethyldith1o- M.P.=26 0.

IS /CH; carbamate. CHr- S (i7-N 122 S 4-methoxy-benzyl'U-plperldlnodlthlo- B.P.=-184 C./0.51 mm.

ll carbamate. Hg. CH|O CH2-SC- H 13: S 0H: 4-6thoxy-benzyl-N,N-dlmethyldithlocarba- B.P.=178180 0.10.05 mm.

H mate. Hg. (M.P.=7880 0.). 021150 CH2SC-N\ 142 S 01H; M.P.=2829 C.

CzHs

4-ethoxy-benzyl-N,N-diethyldlthlocarbamate.

TABLE 2-Continued Compound Structural formula Chemical name Properties 15: S1 /OzH1-i 4-ethtzxy-benzyl-N,N-diisopropyldithioearba- M.P.=8687 0.

X113 6. CzH OCI-IzS-C-N C aHi-i l6: C 211 2-e thoxy-benzyl-N,N-dimethyldithioearba- Oil.

S CH; mate.

i C Hz- S C-N 17 1? /CzHs 4is0ptr0poxybenzyl-N,N-diethyldithioearba- B.P.=174175 C./0.25 mm. Hg. ma 8. rounoQ-om-s C--N 18 S S I-i 4-is0propoxybenzyl-N,N-diisopropyldithio- M.P.= 78-79 C.

II earbamate. i-C3H O- OHr-S -O-N\ sH1-i It Will be realized by the artisan that all of the foregoing compounds contemplated by the present invention possess the desired strong and selective herbicidal properties, and especially the capability of controlling and destroying selectively weeds in rice cultivations, as well as a comparatively low toxicity toward warm-blooded creatures and fish life and a concomitantly low phytotoxicity to higher plants such as rice, and the like, enabling such compounds to be used with correspondingly favorable compatibility with respect to warm-blooded creatures and fish and higher plants for more effective control and/or elimination of weeds by application of such compounds to such weeds and/or their habitat. As contemplated herein, the term Weeds is meant to include not only Weeds in the narrow sense, but also Weeds in the broad sense, whereby to cover all plants and vegetation considered undesirable for the particular purpose in question.

It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention.

What is claimed is:

1. Method of using an alkoxy-benzyl-dithiocarbamic acid ester compound of the formula Q-om-s- 91- z in which R is lower alkyl, and Z is selected from the group consisting of lower alkylamino and dilower alkylamino for selectively controlling weeds, which comprises applying to at least one of '(a) such weeds and (b) their habitat, a herbicidally effective amount of such compound.

2. Method according to claim 1 wherein such compound is used in the form of a mixture with a dispersible carrier vehicle, said compound being present in a toxic amount and constituting substantially between about 0.00195% by weight of the mixture.

3. Method according to claim 1 wherein such compound is selected from the group consisting of:

References Cited UNITED STATES PATENTS 2,992,091 7/1961 Harman et a1. 7ll00 3,202,572 8/1965 Werres et al 260'-455 A 3,532,488 10/1970 Husted 260-455 A FOREIGN PATENTS 633,613 12/1963 Belgium 260455 A 886,426 1/1962 Great Britain 7l--10l OTHER REFERENCES Melnikov et al.: Organic Insectofungicides, etc. (1968), CA69, No. 51760e. (1968).

Matsushima et al.: Dithiocarbamate Esters (1968), CATO, No. 57389h (1969).

Matsushima et al.: Ovicidal Eifects of Aromatic Esters etc. (1966), CA66, No. 43534c (1967).

LEWIS GOTTS, Primary Examiner G. HOLLRAH, Assistant Examiner US. Cl. X.R. 7194 

